A variety of possible cryogenic memory designs for superconductor-based computing have been proposed including memories based on single flux quantum (SFQ) digital logic, hybrid superconducting CMOS (complementary metal oxide semiconductor) designs, and magnetic RAM (random access memory).
Superconducting SFQ digital logic circuits show promise to significantly advance performance in variety of applications including computer processors (e.g., CPUs), memories, digital radio frequency receivers, and other applications. While SFQ technology provides seemingly satisfactory solutions for cryogenic processors, only 4,096 bits of memory have been demonstrated so far. Moreover, when projected to a 1 Petabyte memory, the power dissipation nears 85 Megawatts.
Hybrid memory designs have been proposed to improve upon the low capacity and high dissipation of SFQ-based superconducting RAMs. Such designs include complicated and expensive interfaces between SFQ circuitry and RAM technology such as cryogenic CMOS DRAM or room-temperature memories. Thus, there is ample opportunity in the development of cryogenic memories.